1. Field of the Invention
The present invention relates to a rotating apparatus and in particular to a rotating apparatus in which a permanent magnet is provided within a rotor.
2. Description of Related Art
In a technical report issued July, 1980 by Densigijyutu-sogo-kenkyusho, a turbo expanding apparatus as a rotating apparatus is disclosed. The turbo expanding apparatus has a rotor which is rotated by a working gas such as helium. In the rotor, a permanent magnet is provided. Upon rotation of the rotor, the permanent magnet generates currents in a coil wound on a stator within which the rotor is rotated.
However, since the permanent magnet is connected to the rotor by shrink fitting or an expansion fit, the connecting strength therebetween is insufficient. Thus, during the rotation of the rotor at high speeds, the insufficiency of the connection strength could create an unbalanced condition o separation of the permanent magnet from the rotor.